It was one of the biggest questions hanging over the latest explosive series of BBC One's Line of Duty... who was Balaclava Man?

In the end, the masked murderer was revealed to be just a random thug – though he was in league with two of the suspects, ACC Hilton (Paul Higgins) and Jimmy Lakewell (Patrick Baladi).

But it could've been very different. Speaking exclusively to Digital Spy, series creator Jed Mercurio revealed that he considered a number of alternate endings, including one that revealed a major character to be BM.

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"There was a possibility that Jamie [AC-12's new recruit, played by Royce Pierreson] would be revealed as Balaclava Man," Mercurio said.

Mercurio explained that his ultimate goal for the finale was to "be as neat and conclusive about the things that were unique to series four, but to leave open the things that related to the overall meta-narrative of Line of Duty".

One alternate that the award-winning writer never considered though? Killing off Steve Arnott (Martin Compston).

According to Mercurio, the waistcoat-sporting copper was always intended to survive his assault at Balaclava Man's hands.

"We obviously wanted to create the jeopardy and we wanted to create the uncertainty in the audience's mind," he said. "But I didn't think that it was the right way for the character to exit the series, so Steve will live to fight another day!"

Line of Duty series 4 and complete series 1-4 box set are available now on DVD.